1. Field of the Invention
The present invention relates to a composite nanofiber membrane for the adsorption of lithium, a method for preparing the same, and a lithium recovery apparatus and method using the same. More particularly, the present invention relates to a composite nanofiber membrane for the adsorption of lithium, which is immobilized with manganese oxide selectively adsorptive of lithium, a preparation method thereof, and a lithium recovery apparatus and method using the same.
2. Description of the Related Art
The interest in lithium recovery from natural reservoirs has been driven by its growing demand as a useful core component of high-energy storage batteries for electric vehicles and portable electronic appliances such as smart phones, tablet PCs, etc., which have recently been developed and have risen sharply in demand. Accordingly, with the current worldwide rate of energy consumption, research is now focused on finding other potential sources of lithium such as the seawater, which is estimated to contain approximately 2.5×1014 kg of lithium. However, lithium in seawater (as Li+) is very diluted with an average concentration of 0.17 mg/L in comparison to other cations. Thus, its recovery from seawater requires a highly selective technique for lithium.
So far, one of the most promising methods to sequester lithium ions from seawater is lithium adsorption. In recent years, a variety of inorganic lithium ion-sieves (LIS) such as the spinel-type hydrous manganese oxides derived from lithium manganese oxides have been developed and effectively used as lithium adsorbents. However, the powdered nature of LIS renders them difficult to handle and less recyclable due to their susceptibility to physical loss during post-adsorption retrieval. Therefore, the use of LIS as powdered adsorbents is not economically viable at full-scale application.
To avoid the disadvantages, active studies have been directed toward the immobilization of LIS power on solid supports. Various polymeric materials such as polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polysulfone (PSf), polyurethane (PU) and polyvinylidene fluoride (PVDF) have been used as LIS binders to produce composite Li+ adsorbents in various forms such as granules, macroporous beads, membranes and foams. In order to effectively optimize the adsorbents, however, an improvement should be brought about to resolve problems of high production cost, the generation of secondary wastes during material preparation, and adsorption performance.